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This publication is available free of charge from:https://doi.org/10.6028/NIST.HB.133-2017

INSIDE FRONT COVER - BLANK

Checking the Net Contents of Packaged Goods

as adopted by the 101st National Conference on Weights and Measures 2016

Editors:

Linda Crown David Sefcik

Lisa Warfield

Georgia Harris, Acting Chief Office of Weights and Measures

Physical Measurement Laboratory

This publication is available free of charge from: https://doi.org/10.6028/NIST.HB.133-2017

November 2016

U.S. Department of Commerce Penny Pritzker, Secretary

National Institute of Standards and Technology Willie May, Under Secretary of Commerce for Standards and Technology and Director

NIST Handbook 133

2017 Edition Supersedes NIST Handbook 133, 2016 Edition

https://doi.org/10.6028/NIST.HB.133

Certain commercial entities, equipment, or materials may be identified in this document in order to describe an experimental procedure or concept adequately. Such identification is not intended to imply recommendation or endorsement by the National Institute of Standards and Technology, nor is it intended to imply that the entities, materials, or equipment are necessarily the best available for the purpose.

National Institute of Standards and Technology Handbook 133, 2017 Edition Natl. Inst. Stand. Technol. Handb. 133, 2017 Ed. 248 Pages (Nov. 2016)

CODEN: NIHAE2

U.S. GOVERNMENT PUBLISHING OFFICE WASHINGTON: 2016

Internet: bookstore.gpo.gov Phone: toll free (866) 512-1800; DC area (202) 512-1800 Fax: (202) 512-2250 Mail: Stop SSOP,

Washington, DC 20402-0001 ISBN 0-16-051249-2

iii

Foreword

This handbook has been prepared as a procedural guide for the compliance testing of net content statements on packaged goods. Compliance testing of packaged goods is the determination of the conformance of the results of the packaging, distribution, and retailing process (the packages) to specific legal requirements for net content declarations. This handbook has been developed primarily for the use of government officials. However, it should also be useful to commercial and industrial establishments in the areas of packaging, distribution, and sale of commodities.

In conducting compliance testing, the conversion of quantity values from one measurement system to another (e.g., from the metric system to the avoirdupois system) should be handled with careful regard to the implied correspondence between the accuracy of the data and the number of digits displayed. In all conversions, the number of significant digits retained should ensure that accuracy is neither sacrificed nor exaggerated. For this 2017 edition of Handbook 133 all dimensions for test procedures, devices, or environments have been rounded to two significant digits (e.g., 2.5 cm to 1.0 in) or to a precision level applicable to the test equipment (e.g., 200 kPa for 25 psi and 35 MPa for 5,000 psi).

You are invited to provide online feedback regarding this document at: https://www.surveymonkey.com/s/customer-satisfaction-pub or by e-mail to: [email protected].

https://www.surveymonkey.com/s/customer-satisfaction-pub

iv

THIS PAGE INTENTIONALLY LEFT BLANK

v

Committee Members

Committee on Laws and Regulations of the National Conference on Weights and Measures

Richard Lewis, Georgia

Ethan Bogren, Westchester County, New York Ha Dang, San Diego, California

John Albert, Missouri Louis Sakin, Towns of Hopkinton/Northbridge, Massachusetts

Associate Membership Committee Representative: Rebecca Richardson, MARC – IV Consulting

Canadian Technical Advisor: Lance Robertson, Measurement Canada NIST Technical Advisors: Lisa Warfield, David Sefcik

vi

Past Chairmen of the Committee

Conference

Chairman

Conference

Chairman

41

G. H. Leithauser, MD

71

D. Stagg, AL

42

F. M. Greene, CT

72

A. Nelson, CT

43

F. M. Greene, CT

73

K. Simila, OR

44

G. L. Johnson, KY

74

K. Simila, OR

45

R. Williams, NY

75

S. B. Colbrook, IL

46

J. H. Lewis, WA

76

A. Nelson, CT

47

J. H. Lewis, WA

77

B. Bloch, CA

48

J. H. Lewis, WA

78

F. Clem, OH

49

J. H. Lewis, WA

79

B. Bloch, CA

50

L. Barker, WV

80

S. Rhoades, AZ

51

L. Barker, WV

81

L. Straub, MD

52

M. Jennings, TN

82

S. Millay, ME

53

W. A. Kerlin, CA

83

K. Angell, WV

54

J. F. Lyles, VA

84

K. Angell, WV

55

J. F. Lyles, VA

85

S. Morrison, CA

56

S. D. Andrews, FL 86 R. Williams, TN

57

S. D. Andrews, FL 87 P. D’Errico, NJ

58

S. D. Andrews, FL 88 D. Johannes, CA

59

R. M. Leach, MI 89 D. Johannes, CA

60

R. L. Thompson, MD 90 J. Gomez, NM

61

C. H. Vincent, Dallas, TX 91 J. Benavides, TX

62

C. H. Vincent, Dallas, TX 92 J. Cassidy, MA

63

J. T. Bennett, CT 93 V. Dempsey, OH

64 R. W. Probst, WI 94 J. Gomez, NM

65 D. I. Offner, MO 95 J. Benavides, TX

66 J. J. Bartfai, NY 96 J. Gaccione, NY

67 J. J. Bartfai, NY 97 J. Cardin, WI

68

J. J. Bartfai, NY 98 J. Cardin, WI

69

W. R. Mossberg, CA 99 R. Johnson, NM

70

E. Skluzacek, MN 100 T. Lloyd, MT

vii

Table of Acronyms

Acronym Term Acronym Term AAP Average Adjusted Purge HB 44 NIST Handbook 44, “Specifications,

Tolerances, and Other Technical Requirements for Weighing and Measuring Devices”

AMAV Adjusted Maximum Allowable Variation

LNQC Labeled Net Quantity of Content

ANGW Adjusted Nominal Gross Weight MA Moisture Allowance AOSA Association of Official Seed

Analysts MAV Maximum Allowable Variation

ASEL Adjusted Sample Error Limit MSDS Material Safety Data Sheets ASTM American Society for Testing

Materials International NGW Nominal Gross Weight

CFR Code of Federal Regulations NIST National Institute of Standards and Technology

CGA Compressed Gas Association NCWM National Conference on Weights and Measures

EPA Environmental Protection Agency UME Unreasonable Minus Errors FDA Food and Drug Administration PSEL Purge Sample Error Limit FDCA Food, Drug and Cosmetic Act SCF Sample Correction Factor FPLA Fair Packaging and Labeling Act SEL Sample Error Limit FSIS Food Safety and Inspection Service

of the USDA TTB Alcohol and Tobacco Tax and Trade

Bureau FTC Federal Trade Commission UPLR Uniform Packaging and Labeling

Regulation HB 130 NIST Handbook 130, “Uniform

Laws and Regulations in the areas of Legal Metrology and Engine Fuel Quality”

USDA U.S. Department of Agriculture

HB 133 NIST Handbook 133, “Checking the Net Contents of Packaged Goods”

NCWM National Conference on Weights and Measures

viii


ix

Table of Content

Page

Foreword ...................................................................................................................................................... iii

Committee Members ..................................................................................................................................... v

Past Chairmen of the Committee ................................................................................................................. vi

Table of Acronyms ..................................................................................................................................... vii

2016 Amendments .................................................................................................................................... xvii

2016 Editorial Changes ............................................................................................................................ xviii

Introduction ................................................................................................................................................... 1

A. Source. ............................................................................................................................................. 1 B. Purpose. ............................................................................................................................................ 1 C. Amendments .................................................................................................................................... 1 D. Revisions to the Handbook .............................................................................................................. 2 E. Annotation ....................................................................................................................................... 2 F. Effective Enforcement Dates of Regulations ................................................................................... 2 G. Section References ........................................................................................................................... 2 H. The International System of Units ................................................................................................... 2 I. “Mass” and “Weight.” [NOTE 1, page 3] .................................................................................................. 3 J. Use of the Terms “Mass” and “Weight.” [NOTE 1, page 3] ...................................................................... 3

Chapter 1. General Information ................................................................................................................... 5

Scope ................................................................................................................................................ 5 1.1.1. When and Where to Use Package Checking Procedures .......................................................... 5 a. Point-of Pack ............................................................................................................................. 5 b. Wholesale .................................................................................................................................. 5 c. Retail ......................................................................................................................................... 5 1.1.2. Selecting a Product for Testing ................................................................................................. 6

Package Requirements ..................................................................................................................... 6 1.2.1. Inspection Lot ............................................................................................................................ 6 1.2.2. Average Requirement ................................................................................................................ 7 1.2.3. Individual Package Requirement ............................................................................................... 7 1.2.4. Maximum Allowable Variation ................................................................................................. 7 1.2.5. Exceptions to the Average and Individual Package Requirements ........................................... 7 1.2.6. Deviations Caused by Moisture Loss or Gain ........................................................................... 7

Applying a Moisture Allowance ................................................................................. 8

Sampling Plans ................................................................................................................................ 8 1.3.1. Audit Tests ................................................................................................................................ 9

Other Regulatory Agencies Responsible for Package Regulations and Applicable Requirements . 9

x

Assistance in Testing Operations ................................................................................................... 10

Health and Safety ........................................................................................................................... 10

Good Measurement Practices ........................................................................................................ 10 1.7.1. Traceability Requirements for Measurement Standards and Test Equipment ........................ 10 1.7.2. Certification Requirements for Standards and Test Equipment .............................................. 10

Chapter 2. Test Procedures for Packages Labeled by Weight - Gravimetric Testing ................................ 13

Scope .............................................................................................................................................. 13

Measurement Standards and Test Equipment ................................................................................ 13 2.2.1. Scale Requirements ................................................................................................................. 13 2.2.2. Scale Accuracy ........................................................................................................................ 13 2.2.3. Scale Tolerance ....................................................................................................................... 14 2.2.4. Scale Verification .................................................................................................................... 15

Increasing-Load Test ................................................................................................. 16 Decreasing-Load Test ............................................................................................... 16 Shift Test ................................................................................................................... 16 Return to Zero ........................................................................................................... 16

2.2.5. Other Test Equipment Requirements ...................................................................................... 17

Basic Test Procedure for Gravimetric Testing of Net Weight ....................................................... 17 2.3.1. Define the Inspection Lot ........................................................................................................ 18 2.3.2. Select Sampling Plans ............................................................................................................. 18 2.3.3. Record Inspection Data ........................................................................................................... 18

Procedure for Recording Data ................................................................................... 19 2.3.4. Random Sample Selection ....................................................................................................... 20 2.3.5. Procedures for Determining Tare ............................................................................................ 20 a. Used Dry Tare ......................................................................................................................... 21 b. Unused Dry Tare ..................................................................................................................... 21 c. Wet Tare .................................................................................................................................. 21

Determination of Tare Sample and Average Tare Weight ........................................ 21 2.3.5.1.1. Unused Dry Tare ............................................................................................ 23

Special Procedures for Determining Tare ................................................................. 23 Aerosol Containers ............................................................................................................... 23 Vacuum Packed Coffee ........................................................................................................ 23

2.3.6. Determine Nominal Gross Weight and Package Error ............................................................ 24 Determine Nominal Gross Weight ............................................................................ 24 Determine Package Error .......................................................................................... 24 Compute Total Package Error ................................................................................... 25

2.3.7. Evaluate for Compliance ......................................................................................................... 25 Maximum Allowable Variation (MAV) Requirement .............................................. 25 Average Requirement ............................................................................................... 25

2.3.8. Moisture Allowances ............................................................................................................... 26 Applying Moisture Loss before Determining Package Errors .................................. 26

xi

Applying Moisture Allowance after Determining Package Errors ........................... 29 Moisture Allowance Gray Area ................................................................................ 30

Borax .............................................................................................................................................. 30 2.4.1. Test Equipment........................................................................................................................ 31 2.4.2. Test Procedure ......................................................................................................................... 31

Determination of Drained Weight ................................................................................................. 33 2.5.1. Test Equipment........................................................................................................................ 33 2.5.2. Test Procedure ......................................................................................................................... 33

Net Weight of Encased-in-Ice and Ice Glazed Products ................................................................ 34 2.6.1. Net Weight of Encased-in-Ice and Frozen Block Product ...................................................... 34

Test Equipment ......................................................................................................... 34 Test Procedure for Encased-in-Ice Product Only ...................................................... 35

2.6.2. Net Weight of Ice Glazed Seafood, Meat, Poultry or Similar Products .................................. 36 Test Equipment ......................................................................................................... 36 Test Procedures for Ice Glazed Product Only ........................................................... 36

2.6.3. Evaluation of Results ............................................................................................................... 37

Determining the Net Weight and Percentage of Purge in Packages or Fresh and Frozen Chitterlings ..................................................................................................................................... 37

2.7.1. Test Equipment........................................................................................................................ 37 2.7.2. Test Procedure for Net Weight and Purge Determination for Fresh and Frozen Chitterlings. 38

Net Weight and Purge Determinations ..................................................................... 38 2.7.2.1.1. Test Procedure for Determining the Net Weight and Purge from Fresh and

Frozen Chitterlings ......................................................................................... 39 2.7.3. Evaluations of Results – Compliance Determinations ............................................................ 41 a. Individual Package Requirement ............................................................................................. 41 b. Average Error Requirement .................................................................................................... 42

Chapter 3. Test Procedures – For Packages Labeled by Volume .............................................................. 45

Scope .............................................................................................................................................. 45 3.1.1. Test Methods ........................................................................................................................... 45

Gravimetric Test Procedure for Non-Viscous Liquids .................................................................. 46 3.2.1. Test Equipment........................................................................................................................ 46 3.2.2. Test Procedure ......................................................................................................................... 47 3.2.3. Evaluation of Results ............................................................................................................... 49

Volumetric Test Procedure for Non-Viscous Liquids ................................................................... 49 3.3.1. Test Equipment........................................................................................................................ 49 3.3.2. Test Procedure ......................................................................................................................... 50 3.3.3. Evaluation of Results ............................................................................................................... 50

Volumetric Test Procedures for Viscous Fluids – Headspace ....................................................... 50 3.4.1. Test Equipment........................................................................................................................ 50 3.4.2. Test Procedures ....................................................................................................................... 51

xii

a. Test Procedure for Testing Oils, Syrups, and other Viscous Liquids with a Smooth and Level Surface ........................................................................................................................... 51

b. Test Procedure for Testing Mayonnaise, Salad Dressing, and Water Immiscible Products with no Smooth and Level Surface ......................................................................................... 52


Goods Labeled by Capacity – Volumetric Test Procedure ............................................................ 53 3.5.1. Test Equipment........................................................................................................................ 53 3.5.2. Test Procedure ......................................................................................................................... 53 3.5.3. Evaluation of Results ............................................................................................................... 53

Pressed and Blown Glass Tumblers and Stemware ....................................................................... 54 3.6.1. Test Equipment........................................................................................................................ 54 3.6.2. Test Procedure ......................................................................................................................... 54 3.6.3. Evaluation of Results ............................................................................................................... 54

Volumetric Test Procedure for Paint, Varnish, and Lacquers – Non-aerosol ................................ 55 3.7.1. Test Equipment........................................................................................................................ 55 3.7.2. Test Procedures ....................................................................................................................... 55 a. Field (Retail) Auditing Procedure ........................................................................................... 55 b. Plant Audit Test Procedure ...................................................................................................... 58 c. Violation Procedure ................................................................................................................. 59 3.7.3. Evaluation of Results ............................................................................................................... 61

Testing Viscous Materials – Such As Caulking Compounds and Pastes ....................................... 61 3.8.1. Test Equipment........................................................................................................................ 61 3.8.2. Test Procedure ......................................................................................................................... 61 3.8.3. Evaluation of Results ............................................................................................................... 62

Peat Moss ....................................................................................................................................... 63 3.9.1. Dimensional Test Procedure for Compressed Quantity .......................................................... 63

Test Equipment ......................................................................................................... 63 Test Procedure........................................................................................................... 64

3.9.2. Uncompressed Volume Packages............................................................................................ 69 Test Equipment ......................................................................................................... 69 Test Procedure........................................................................................................... 69


Mulch and Soils Labeled by Volume ............................................................................................. 70 3.10.1. Test Equipment........................................................................................................................ 70 3.10.2. Test Procedure ......................................................................................................................... 72 3.10.3. Evaluation of Results ............................................................................................................... 72

Ice Cream Novelties ....................................................................................................................... 72 3.11.1. Test Equipment........................................................................................................................ 73 3.11.2. Test Procedure ......................................................................................................................... 73 3.11.3. Evaluation of Results ............................................................................................................... 76

xiii

Fresh Oysters Labeled by Volume ................................................................................................. 76 3.12.1. Test Equipment........................................................................................................................ 76 3.12.2. Test Procedure ......................................................................................................................... 77 3.12.3. Evaluation of Results ............................................................................................................... 78

Determining the Net Contents of Compressed Gas in Cylinders ................................................... 78 3.13.1. Test Equipment........................................................................................................................ 79 3.13.2. Test Procedures ....................................................................................................................... 80 a. Test Procedure for Cylinders Labeled by Weight ................................................................... 80 b. Test Procedure for Cylinders Labeled by Volume .................................................................. 81 3.13.3. Evaluation of Results ............................................................................................................... 81

Firewood – Volumetric Test Procedure for Packaged Firewood with a Labeled Volume of 113 L [4 ft3] or Less and Stacked Firewood Sold by the Cord or Fractions of a Cord. ........................... 81

3.14.1. Test Equipment........................................................................................................................ 82 3.14.2. Test Procedure ......................................................................................................................... 82 a. Boxed Firewood ...................................................................................................................... 85 b. Stacked Firewood .................................................................................................................... 89 c. Bundles and Bags .................................................................................................................... 93 3.14.3. Evaluation of Results ............................................................................................................... 97

Test Procedure for Verifying the Useable Volume Declaration on Packages of Animal Bedding 99 3.15.1. Test Equipment........................................................................................................................ 99 3.15.2. Test Procedure ....................................................................................................................... 104

Chapter 4. Test Procedures – Packages Labeled by Count, Linear Measure, Area, Thickness, and Combinations of Quantities ......................................................................................................... 117

Scope ............................................................................................................................................ 117

Packages Labeled by Count ......................................................................................................... 117 4.2.1. Packages Labeled with 50 Items or Fewer ............................................................................ 117

Test Equipment ....................................................................................................... 117 Test Procedure......................................................................................................... 117 Evaluation of Results .............................................................................................. 117

4.2.2. Packages Labeled by Count of More than 50 Items .............................................................. 118 Test Equipment ....................................................................................................... 118 Test Procedures ....................................................................................................... 119

Audit Procedure ................................................................................................................. 119 Violation Procedure ........................................................................................................... 120

Evaluation of Results .............................................................................................. 122

Paper Plates and Sanitary Paper Products .................................................................................... 122 4.3.1. Test Equipment...................................................................................................................... 122 4.3.2. Test Procedure ....................................................................................................................... 123 4.3.3. Evaluation of Results ............................................................................................................. 123

Special Test Requirements for Packages Labeled by Linear or Square Measure (area) .............. 124

xiv

Polyethylene Sheeting .................................................................................................................. 124 4.5.1. Test Equipment...................................................................................................................... 124 4.5.2. Test Procedure ....................................................................................................................... 125 4.5.3. Evaluation of Results ............................................................................................................. 128 a. Individual Thickness ............................................................................................................. 128 b. Average Thickness ................................................................................................................ 128

Packages Labeled by Linear or Square (area) Measure ............................................................... 129 4.6.1. Test Equipment...................................................................................................................... 129 4.6.2. Test Procedure ....................................................................................................................... 129 4.6.3. Evaluation of Results ............................................................................................................. 131

Baler Twine – Test Procedure for Length .................................................................................... 131 4.7.1. Test Equipment...................................................................................................................... 131 4.7.2. Test Procedure ....................................................................................................................... 131 4.7.3. Evaluation of Results ............................................................................................................. 133

Procedure for Checking the Area Measurement of Chamois....................................................... 133 4.8.1. Template Test Method (for field audits) ............................................................................... 133

Test Equipment ....................................................................................................... 133 Test Procedure......................................................................................................... 133

4.8.2. Gravimetric Procedure for Area Measurement ..................................................................... 134 Test Equipment ....................................................................................................... 134 Test Procedure......................................................................................................... 135

4.8.3. Evaluation of Results ............................................................................................................. 136

Procedure for Checking the Contents of Specific Agriculture Seed Packages Labeled by Count ............................................................................................................................................ 136

4.9.1. Test Equipment...................................................................................................................... 136 4.9.2. Test Procedure ....................................................................................................................... 136 4.9.3. Evaluation of Results ............................................................................................................. 138

Appendix A. Tables ................................................................................................................................. 139

Table 1-1. Agencies Responsible for Package Regulations and Applicable Requirements .............. 139 Table 2-1. Sampling Plans for Category A ........................................................................................ 141 Table 2-2. Sampling Plans for Category B ......................................................................................... 141 Table 2-3. Category A ........................................................................................................................ 142 Table 2-4. Category B ........................................................................................................................ 145 Table 2-5. Maximum Allowable Variations (MAVs) for Packages Labeled by Weight ................... 146 Table 2-6. Maximum Allowable Variations (MAVs) for Packages Labeled by Liquid and Dry

Volume .................................................................................................................................. 148 Table 2-7. Maximum Allowable Variations (MAVs) for Packages Labeled by Count ..................... 151 Table 2-8. Maximum Allowable Variations (MAVs) for Packages Labeled by Length, Width, or

Area ....................................................................................................................................... 152 Table 2-9. U.S. Department of Agriculture, Meat and Poultry Groups and Lower Limits for Individual

Packages (Maximum Allowable Variations [MAVs]) .......................................................... 153

xv

Table 2-10. Exceptions to the Maximum Allowable Variations (MAVs) for Textiles, Polyethylene Sheeting and Film, Mulch and Soil Labeled by Volume, Packaged Firewood Labeled in Terms of Volume, and Packages Labeled by Count with 50 Items or Fewer, and Specific Agricultural Seeds Labeled by Count. ....................... 154

Table 2-11. Sampling Plans and Accuracy Requirements for Packages Labeled by Low Count (50 or Fewer) and Packages Given Tolerances (Glass and Stemware) ............................................ 155

Appendix B. Random Number Tables ..................................................................................................... 157

Appendix C. Model Inspection Report Forms ......................................................................................... 165

Random Package Report .................................................................................................................... 167 Random Package Report – Example .................................................................................................. 168 Standard Package Report .................................................................................................................... 169 Standard Package Report – Example ................................................................................................. 170 Standard Package Report Animal Bedding ...................................................................................... 171 Measurement Grid and Package Error Worksheet for Cylindrical and Square or Rectangular Test

Measures ................................................................................................................................ 172 Ice Glazed Package Worksheet .......................................................................................................... 173 Ice Glazed Package Worksheet – Example ........................................................................................ 174 Ice Glazed Package Report ................................................................................................................. 175 Ice Glazed Package Report – Example .............................................................................................. 176 Determining the Free Liquid and Net Volume of Oysters Worksheet ............................................... 177 Determining the Free Liquid and Net Volume of Oysters Worksheet – Example ............................ 178 Peat Moss Labeled by Volume Package Worksheet – Dimensional Procedure ................................. 183 Borax Audit Worksheet ...................................................................................................................... 184

Appendix D. AOSA Rules for Testing Seeds .......................................................................................... 185

AOSA Rules for Testing Seeds – Section 2: Preparation of Working Samples ................................ 185 AOSA Rules for Testing Seeds – Section 12: Mechanical Seed Count ............................................. 189

Appendix E. General Tables of Units of Measurement ........................................................................... 191

Section 1. Tables of Metric Units of Measurement ................................................................................. 191 Units of Length ................................................................................................................................... 191 Units of Area ...................................................................................................................................... 192 Units of Liquid Volume ..................................................................................................................... 192 Units of Volume ................................................................................................................................. 192 Units of Mass ...................................................................................................................................... 192

Section 2. Tables of U.S. Units of Measurement ..................................................................................... 193 Units of Length ................................................................................................................................... 193 Units of Area ...................................................................................................................................... 193 Units of Volume3 ................................................................................................................................ 194 Gunter’s or Surveyors Chain Units of Measurement ......................................................................... 194 Units of Liquid Volume ..................................................................................................................... 194 Apothecaries Units of Liquid Volume ............................................................................................... 194 Units of Dry Volume .......................................................................................................................... 195

xvi

Avoirdupois Units of Mass ................................................................................................................. 195 Troy Units of Mass ............................................................................................................................. 196 Apothecaries Units of Mass................................................................................................................ 196

Section 3. Notes on British Units of Measurement .................................................................................. 197

Section 4. Tables of Units of Measurement ............................................................................................. 198 Units of Length – International Measure ............................................................................................ 198 Units of Length – Survey Measure9 ................................................................................................... 198 Units of Area – International Measure ............................................................................................... 199 Units of Area – Survey Measure10 ...................................................................................................... 200 Units of Volume ................................................................................................................................. 201 Units of Capacity or Volume – Dry Volume Measure ....................................................................... 202 Units of Capacity or Volume – Liquid Volume Measure .................................................................. 203 Units of Mass Not Less Than Avoirdupois Ounces ........................................................................... 204 Units of Mass Not Greater Than Pounds and Kilograms ................................................................... 205

Section 5. Tables of Equivalents .............................................................................................................. 207 Units of Length ................................................................................................................................... 208 Units of Area ...................................................................................................................................... 209 Units of Capacity or Volume .............................................................................................................. 210 Units of Mass ...................................................................................................................................... 212

Appendix F. Glossary .............................................................................................................................. 215

Index ..................................................................................................................................................... 223

References ................................................................................................................................................. 229

file://elwood.nist.gov/68_PML/680/users/crown/My%20Documents/17-Handbook%20133/01-LC%20Work%20file/h133-17-LC20-graphic%20changes%20added%20Lisa%20chgs(rd2).docx#_Toc465168095

xvii

2016 Amendments

The following table indicates the items amended by the 101th (2016) National Conference on Weights and Measures (NCWM). As appropriate, the text on the cited pages indicates the changes to a Handbook 133 section, or paragraph as “Added 2016” or “Amended 2016.” Unless otherwise noted, the effective date of the regulations added or amended in 2016 is January 1, 2017.

Chapter L&R

Committee Item No.

Section Action Page

Chapter 2. Test – Labeled by Weight – Gravimetric Testing

260-2

2.4. Borax Audit Test Amended 30

2.4.1. Test Equipment Amended 31

2.4.2. Test Procedure Amended 31

Chapter 3. Test Procedures – For Packages Labeled by Volume

260-3

3.14. Firewood – (Volumetric Test Procedure for Packaged Firewood with a Labeled Volume of 113 L [4 ft3] or Less)

Amended 81

3.14.1. Test Equipment Amended 82

3.14.2. Test Procedure Amended 82

a. Boxed Firewood Amended 85

b. Crosshatched Stacked Firewood

Amended 89

c. Bundles and Bags of Firewood

Amended 93

3.14.3. Evaluation of Results Amended 97

260-5

3.15. Test Procedure for Verifying the Usable Volume Declaration on Packages of Animal Bedding

Added 99

3.15.1. Test Equipment Added 99

3.15.2. Test Procedure Added 104

Appendix C. Model Inspection Report Forms

260-2 Borax Audit Worksheet Added 184

260-5

Standard Package Report – Animal Bedding

Added 165

Measurement Grid and Package Error Worksheet for Cylindrical and Square or Rectangular Test Measures

Added 171

xviii

2016 Editorial Changes

The following items were deemed editorial in nature based on the following criteria: 1) the modified text did not change the meaning or procedure outlined, 2) modified text corrected an omission or clarified how the text was written, or 3) the item itself was reformatted and relocated in the text to make the organization of the content more meaningful.

Chapter Section Action Page

Chapter 3. Test Procedures – For Packages Labeled by Volume

3.1.1. Test Methods

Table 3-1. Updated table to reflect the change in the references to the Code of Federal Regulations sections for frozen food, refrigerated food, and other liquids.

46

3.9.1.2. Test Procedure

List Item 5. Corrected the picture identity in paragraph. Changed Exhibit 4 to Figure 3-5.

63

Figure 3-5. Added “Height Measurement” to picture label.

65

Appendix C. Model Inspection Report Forms

Chitterlings Worksheet – Category A – Example

Updated 180

Appendix E. General Tables of Units of Measurement

Units of Area – International Measure

Corrected format of “1 square inch” and “1 square meter”

199

Introduction

1

Introduction

A. Source.

The information and procedures in this handbook comprise all of those adopted by the National Conference on Weights and Measures, Inc. (NCWM) www.ncwm.net. Contact NCWM at:

1135 M Street, Suite 100 Phone: (402) 434-4880 E-mail: [email protected] Lincoln, NE 68508 Fax: (402) 434-4878 URL: www.ncwm.net

The NCWM is supported by the National Institute of Standards and Technology (NIST), which provides its Executive Secretary and publishes its documents. NIST also develops technical publications for use by weights and measures agencies; these publications may subsequently be endorsed or adopted by the NCWM.

This handbook is recommended by NCWM for adoption by states when reviewing or amending their official laws and regulations on testing the net contents of packaged goods. A similar recommendation is made with regard to the local jurisdictions within a state in the absence of the promulgation of such laws and regulations at the state level.

B. Purpose.

This handbook has been prepared as a procedural guide for the compliance testing of net content statements on packaged goods. Compliance testing of packaged goods is the determination of the conformance of the results of the packaging, distribution, and retailing process (the packages) to specific legal requirements for net content declarations. This handbook has been developed primarily for the use of government officials. However, commercial and industrial establishments packaging, distributing, and selling commodities will find this handbook useful.

In conducting compliance testing, the conversion of quantity values from one measurement system to another (e.g., from the metric system to the U.S. customary system) should be handled with careful regard to the implied correspondence between the accuracy of the data and the number of digits displayed. In all conversions, the number of significant digits retained should ensure that accuracy is neither sacrificed nor exaggerated. For this 2017 edition of NIST Handbook 133, “Checking the Net Content of Packaged Goods” all dimensions for test procedures, devices, or environments have been rounded to two significant digits (e.g., 2.5 cm to 1.0 in) or to a precision level applicable to the test equipment (e.g., 200 kPa for 25 psi and 35 MPa for 5000 psi).

C. Amendments

Amendments to NIST Handbook 133 are deliberated and developed by NCWM’s Committee on Laws and Regulations before presentation to the general membership for a vote. In some instances, amendments that significantly affect other NIST Handbooks may be processed jointly by two or more committees.

Amendments to the handbooks are made in accordance with NCWM procedures and policies. The process begins at the regional weights and measures association meetings in the fall of each year and is culminated at the NCWM Annual Meeting in July. After passing through one or more of the regional associations, the proposed amendment is placed on the agenda of the appropriate NCWM committee for consideration at the NCWM’s Interim Meeting in January. After final deliberation and development by the committee, the

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Handbook 133, Checking the Net Contents of Packaged Goods (2017)

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amendment may be presented to the membership for a vote at the NCWM Annual Meeting in July. The NCWM policy provides for exceptions to the process to accommodate urgent or priority items. NIST staff provides technical assistance and advice throughout the process.

The policy is available on the NCWM website at www.ncwm.net. For information on the regional weights and measures associations, visit www.ncwm.net/resource/regional_associations.

D. Revisions to the Handbook

NIST publishes a new edition of this handbook after significant changes are made. If NIST determines that amendments made by NCWM were minor or editorial in nature an annual publication will not be published. Instead, NIST will issue a notice that the current edition is still valid and will publish a list of the changes on the NIST website.

E. Annotation

Beginning in 1971, amendments or additions to sections in the handbook are annotated at the end of each section (e.g., “Amended 1982”) as a service to those states that are planning to update their own laws or regulations. The references to each revision and the year will enable government officials and industry members to trace the rationale for the changes by referring to the “Report of the XXX National Conference on Weights and Measures (also known as the NCWM Annual Report) for the year indicated and make decisions regarding adoptions and amendments to their laws and regulations.

F. Effective Enforcement Dates of Regulations

Unless otherwise specified, new or amended sections are intended to become effective and subject to enforcement on January 1 of the year following adoption by NCWM.

G. Section References

In most references made to specific sections or subsections in this handbook, the word “Section” followed by the section number is used.

H. The International System of Units

The “International System of Units,” “SI,” or “SI Units” means the modernized metric system as established in 1960 by the General Conference on Weights and Measures (GIPM). In 1988, Congress amended the Metric Conversion Act of 1975 (see Section 5164 of Public Law 100-418) to declare that it is the policy of the United States to designate the metric system of measurement as the preferred measurement system for U.S. trade and commerce, and it further defined “the metric system of measurement” to be the International System as established by the GIPM and as interpreted or modified for the United States by the Secretary of Commerce. (See Metric Conversion Law 15 U.S.C. 205; NIST Special Publication (SP) 330, “The International System of Units (SI); NIST SP 814, “Guide for the Use of the International System of Units (SI); Interpretation of the International System of Units [the Metric System of Measurement] for the United States in the “Federal Register” of May 16, 2008, [“Federal Register” Vol. 73, No. 96] or subsequent revisions). In 1992, Congress amended the Federal Fair Packaging and Labeling Act (FPLA) to require certain consumer commodities to include the appropriate SI units along with the customary inch-pound units in their quantity statements.

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Introduction

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I. “Mass” and “Weight.” [NOTE 1, page 3]

The mass of an object is a measure of the object’s inertial property or the amount of matter it contains. The weight of an object is a measure of the force exerted on the object by gravity or the force needed to support it. The pull of gravity on the earth gives an object a downward acceleration of about 9.8 m/s2. In trade and commerce and everyday use, the term “weight” is often used as a synonym for “mass.” The “net mass” or “net weight” declared on a label indicates that the package contains a specific amount of commodity exclusive of wrapping materials. The use of the term “mass” is predominant throughout the world and is becoming increasingly common in the United States.

J. Use of the Terms “Mass” and “Weight.” [NOTE 1, page 3]

When used in this handbook, the term “weight” means “mass.” The term “weight” appears when U.S. customary units are cited or when both inch-pound and SI units are included in a requirement. The terms “mass” or “masses” are used when only SI units are cited in a requirement. The following note appears where the term “weight” is first used in a law or regulation.

NOTE 1: When used in this law (or regulation), the term “weight” means “mass.” (See paragraphs I. “Mass” and Weight and J. Use of the Terms “Mass” and “Weight” in the Introduction section of NIST Handbook 133 for an explanation of these terms.) (Introduction added 2015)


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Chapter 1. General Information

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Scope

Routine verification of the net contents of packages is an important part of any weights and measures program to facilitate value comparison and fair competition. Consumers have the right to expect packages to bear accurate net content information. Those manufacturers whose products are sold in packages have the right to expect that their competitors will be required to adhere to the same laws and regulations.

The procedures in this handbook are recommended for use to verify the net quantity of contents of packages kept, offered, or exposed for sale, or sold by weight, measure (including volume, and dimensions), or count at any location (e.g., at the point-of-pack, in storage warehouses, retail stores, and wholesale outlets).

1.1.1. When and Where to Use Package Checking Procedures

An effective program will typically include testing at each of the following levels.

Testing packages at the “point-of-pack” has an immediate impact on the packaging process. Usually, a large number of packages of a single product are available for testing at one place. This allows the inspector to verify that the packer is following current good packaging practices. Inspection at the point-of-pack also provides the opportunity to educate the packer about the legal requirements that products must meet, and may permit resolution of any net content issues or other problems that arise during the testing. Point-of-pack testing is not always possible because packing locations can be in other states or countries. Work with other state, county, and city jurisdictions to encourage point-of-pack inspection on products manufactured in their geographic jurisdictions. Point-of-pack inspections cannot entirely replace testing at wholesale or retail outlets, because this type of inspection does not include imported products or the possible effects of product distribution and moisture loss. Point-of-pack inspections only examine the manufacturing process. Therefore, an effective testing program will also include testing at wholesale and retail outlets.

Testing packages at a distribution warehouse is an alternative to testing at the point-of-pack with respect to being able to test large quantities of, and a variety of products. Wholesale testing is a very good way to monitor products imported from other countries and to follow up on products suspected of being under filled or underweight based on consumer complaints or findings made during other inspections, including those done at retail outlets.

Testing packages at retail outlets evaluates the soundness of the manufacturing, distributing, and retailing processes of the widest variety of goods at a single location. It is acceptable and practical for weights and measures jurisdictions to monitor packaging procedures and to detect present or potential problems. Generally, retail package testing is not conducive to checking large quantities of individual products of any single production lot. Therefore, follow-up inspections of a particular brand or lot code number at a number of retail and wholesale outlets, and ultimately at the point-


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of-pack are extremely important aspects in any package-checking scheme. After the evaluation of an inspection lot is completed, the jurisdiction should consider what, if any, further investigation or follow-up is warranted. At the point-of-sale, a large number of processes may affect the quality or quantity of the product. Therefore, there may be many reasons for any inspection lot being out of compliance. A shortage in weight or measure may result from mishandling the product in the store or the retailer’s failure to rotate stock. Shortages may also be caused through mishandling by a distributor or failure of some part of the packaging process. Shortages may also be caused by moisture loss (desiccation) if the product is packaged in permeable media. Therefore, being able to determine the cause of an error in order to correct defects is more difficult when retail testing is used.

(Amended 2010)

1.1.2. Selecting a Product for Testing

Any commodity sold by weight, measure, or count may be tested. The product to be tested may be chosen in several ways. The decision may be based on different factors, such as (1) marketplace surveys (e.g., jurisdiction-wide surveys of all soft drinks or breads), (2) surveys based on sales volume, or (3) audit testing (see Section 1.3. “Sampling Plans”) to cover as large a product variety as possible at food, farm, drug, hardware stores, or specialty outlets, discount and department stores. Follow-up of possible problems detected in audit testing or in review of past performance tends to concentrate inspection resources on particular commodity types, brand names, retail or wholesale locations, or even particular neighborhoods. The expected benefits for the public must be balanced against the cost of testing. Expensive products should be tested because of their cost per unit. However, inexpensive items should also be tested because the overall cost to individual purchasers may be considerable over an extended period of time. Store packaged items, which are usually perishable and not subject to other official monitoring, should be routinely tested because they are offered for sale where they are packed. Products on sale and special products produced for local consumption should not be overlooked because these items sell quickly in large amounts.

Regardless of where the test occurs, remember that it is the inspector’s presence in the marketplace through routine unannounced testing that ensures equity and fair competition in the manufacturing and distribution process. Finally, always follow-up on testing to ensure that the problems are corrected; otherwise, the initial testing may be ineffective.

Package Requirements

The net quantity of content statement must be “accurate,” but reasonable variations are permitted. Variations in package contents may be a result of deviations in filling. The limits for acceptable variations are based on current good manufacturing practices in the weighing, measuring, and packaging process. The first requirement is that accuracy is applied to the average net contents of the packages in the lot. The second requirement is applied to negative errors in individual packages. These requirements apply simultaneously to the inspection of all lots of packages except as specified in Section 1.2.5. “Exceptions to the Average and Individual Package Requirements.”

1.2.1. Inspection Lot

An “inspection lot” (called a “lot” in this handbook) is defined as a collection of identically labeled (except for quantity or identity in the case of random packages) packages available for inspection at one time. The collection of packages will pass or fail as a whole based on the results of tests on a sample drawn from the lot. This handbook describes procedures to determine if the packages in an


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“inspection lot” contain the declared net quantity of contents and if the individual packages’ variations are within acceptable limits.

1.2.2. Average Requirement

In general, the average net quantity of contents of packages in a lot must at least equal the net quantity of contents declared on the label. Plus or minus variations from the declared net weight, measure, or count are permitted when they are caused by unavoidable variations in weighing, measuring, or counting the contents of individual packages that occur in current good manufacturing practice. Such variations must not be permitted to the extent that the average of the quantities in the packages of a particular commodity or a lot of the commodity that is kept, offered, exposed for sale, or sold, is below the stated quantity. (See Section 3.6. “Pressed and Blown Glass Tumblers and Stemware” and Section 4.2.1. “Packages Labeled with 50 Items or Fewer” for exceptions to this requirement.)

1.2.3. Individual Package Requirement

The variation of individual package contents from the labeled quantity must not be “unreasonably large.” In this handbook, packages that are under filled by more than the Maximum Allowable Variation (MAV) specified for the package are considered unreasonable errors. Unreasonable shortages are not generally permitted, even when overages in other packages in the same lot, shipment, or delivery compensate for such shortage. This handbook does not specify limits of overfilling (with the exception of textiles), which is usually controlled by the packer for economic, compliance, and other reasons. (Amended 2010)

1.2.4. Maximum Allowable Variation

The limit of the “reasonable minus variation” for an under filled package is called a “Maximum Allowable Variation” (MAV). An MAV is a deviation from the labeled weight, measure, or count of an individual package beyond which the deficiency is considered an unreasonable minus error. Each sampling plan limits the number of negative package errors permitted to be greater than the MAV. (Amended 2010)

1.2.5. Exceptions to the Average and Individual Package Requirements

There is an exemption from the average requirement for packages labeled by count with 50 items or fewer. The reason for this exemption is that the package count does not follow a “normal” distribution even if the package is designed to hold the maximum count indicated by the label declaration (e.g., egg cartons and packages of chewing gum). Another exception permits an “allowable difference” in the capacity of glass tumblers and stemware because mold capacity doesn’t follow a normal distribution.

1.2.6. Deviations Caused by Moisture Loss or Gain

Deviations from the net quantity of contents caused by the loss or gain of moisture from the package are permitted when they are caused by ordinary and customary exposure to conditions that normally occur in good distribution practice and that unavoidably result in change of weight or measure. According to regulations adopted by the U.S. Environmental Protection Agency, no moisture loss is recognized on pesticides. (See Code of Federal Regulations 40 CFR Part 156.10.)


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Applying a Moisture Allowance

Some packaged products may lose or gain moisture and, therefore, lose or gain weight or volume after packaging. The amount of moisture loss depends upon the nature of the product, the packaging material, the length of time it is in distribution, environmental conditions, and other factors. Moisture loss may occur even when manufacturers follow good distribution practices. Loss of weight “due to exposure” may include solvent evaporation, not just loss of water. For loss or gain of moisture, the moisture allowances may be applied before or after the package errors are determined.

To apply an allowance before determining package errors, adjust the Nominal Gross Weight (see Section 2.3.6. “Determine Nominal Gross Weight and Package Errors”), so the package errors are increased by an amount equal to the moisture allowance. This approach is used to account for moisture loss in both the average and individual package errors.

It is also permissible to apply the moisture allowances after individual package errors and average errors are determined.

Example: A sample of a product that could be subject to moisture loss might fail because the average error is minus or the error in several of the sample packages are found to be unreasonable errors (i.e., the package error is greater than the Maximum Allowable Variation (MAV) permitted for the package’s labeled quantity).

You may apply a moisture allowance after determining the package errors by adding the allowance to the Sample Error Limit (SEL) and then, comparing the average error to the SEL to determine compliance. The moisture allowance must be added to the MAV before evaluating sample errors to identify unreasonable minus errors. (Amended 2010)

This handbook provides “moisture allowances” for some meat and poultry products, flour, pasta, and dry pet food. (See Chapter 2, Table 2-3. “Moisture Allowances”) These allowances are based on the premise that when the average net weight of a sample is found to be less than the labeled weight, but not by an amount that exceeds the allowable limit, either the lot is declared to be within the moisture allowance or more information must be collected before deciding lot compliance or noncompliance.

Test procedures for flour, some meat, and poultry are based on the concept of a “moisture allowance” also known as a “gray area” or “no decision” area (see Section 2.3.8. “Moisture Allowances”). When the average net weight of a sample is found to be less than the labeled weight, but not more than the boundary of the “gray area,” the lot is said to be in the “gray” or “no decision” area. The gray area is not a tolerance. More information must be collected before lot compliance or noncompliance can be decided. Appropriate enforcement should be taken on packages found short weight and outside of the “moisture allowance” or “gray area.” (Amended 2002)

Sampling Plans

This handbook contains two sampling plans used to inspect packages: “Category A” and “Category B.” Use the “Category B” Sampling Plans to test meat and poultry products at point-of-pack locations that are


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subject to U.S. Department of Agriculture Food Safety and Inspection Service (FSIS) requirements. When testing all other packages, use the “Category A” Sampling Plan.

Inspections by weights and measures officials must provide the public with the greatest benefit at the lowest possible cost. Sampling reduces the time to inspect a lot of packages, so a greater number of items can be inspected. Net content inspection, using sampling plans for marketplace surveillance, protects consumers who cannot verify the net quantity of contents of the package they purchase. This ensures fair trade practices and maintains a competitive marketplace. It also encourages manufacturers, distributors, and retailers to follow good manufacturing and distribution practices.

Testing a “sample” of packages from a lot instead of every package is efficient, but the test results have a “sampling variability” that must be corrected before determining if the lot passes or fails. The “Category A” sampling plans give acceptable lots a 97.5 % probability of passing. An “acceptable” lot is defined as one in which the “average” net quantity of contents of the packages equals or exceeds the labeled quantity. The “Category B” sampling plans give acceptable lots at least a 50 % probability of passing. The sampling plans used in this handbook are statistically valid. That means the test acceptance criteria are statistically adjusted, so they are both valid and legally defensible. This handbook does not discuss the statistical basis, risk factors, or provide the operating characteristic curves for the sampling plans. For information on these subjects, see explanations on “acceptance sampling” in statistical reference books.

A randomly selected sample is necessary to ensure statistical validity and reliable data. This is accomplished by using random numbers to determine which packages are chosen for inspection. Improper collection of sample packages can lead to bias and unreliable results.

1.3.1. Audit Tests

Audits may be used to speed the process of detecting possible net content violations. These audit procedures may include:

• using smaller sample sizes; • using tare lists provided by manufacturers to spot check; or • selecting samples without collecting a random sample.

These audit procedures allow spot checking of more products than is possible with the more structured techniques, but do not take the place of “Category A” or “Category B” testing.

Do not take enforcement action using audit test results. If, after an audit test, there is suspicion that the package lot is not in compliance, use the appropriate “Category A” or “Category B” sampling plan to determine if the lot complies with the package requirements.

Other Regulatory Agencies Responsible for Package Regulations and Applicable Requirements

In the United States, several federal agencies issue regulations regarding package labeling and net contents. The U.S. Department of Agriculture (USDA) regulates meat and poultry. The Food and Drug Administration (FDA) regulates food, drugs, cosmetic products, and medical devices under the Food, Drug, and Cosmetic Act (FDCA) and the Fair Packaging and Labeling Act (FPLA). The Federal Trade Commission (FTC) regulates most non-food consumer packaged products as part of the agency’s responsibility under the FPLA. The Environmental Protection Agency (EPA) regulates pesticides. The Bureau of Alcohol and Tobacco Tax and Trade Bureau (TTB) in the U.S. Department of the Treasury promulgates regulations for packaged tobacco and alcoholic beverages as part of its responsibility under the Federal Alcohol Administration Act.


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Packaged goods produced for distribution and sale also come under the jurisdiction of state and local weights and measures agencies that adopt their own legal requirements for packaged goods. Federal statutes set requirements that pre-empt state and local regulations that are or may be less stringent or not identical to federal regulation depending on the federal law that authorizes the federal regulation. The application of Handbook 133 procedures occurs in the context of the concurrent jurisdiction among federal, state, and local authorities. Therefore, all agencies using this handbook should keep abreast of the revisions to federal agency regulations that may contain sampling or testing information not in the regulations at the time of publication of this handbook. (See Appendix A, Table 1-1. “Agencies Responsible for Package Regulations and Applicable Requirements” for information on the responsible agencies for package regulations. The requirements of this handbook must be used when testing products concurrently subject to pre-emptive federal regulations.)

Assistance in Testing Operations

If the storage, display, or location of any lot of packages requires special equipment or an abnormal amount of labor for inspection, the owner or the operator of the business must supply the equipment and/or labor as required by the weights and measures official.

Health and Safety

This handbook cannot address all of the health and safety issues associated with its use. The inspector is responsible for determining the appropriate safety and health practices and procedures before starting an inspection (e.g., contact the establishment’s health and safety official). Comply with all handling, health, and safety warnings on package labels and those contained in any associated material safety data sheets (MSDS). The inspector must also comply with federal, state, and local health and safety laws, and other appropriate requirements in effect at the time and location of the inspection. Contact your supervisor to obtain information regarding your agency’s health and safety policies and to obtain appropriate safety equipment.

Good Measurement Practices

The procedures in this handbook are designed to be technically sound and represent good measurement practices. To assist in documenting tests, we have included “model” inspection report forms designed to record the information.

1.7.1. Traceability Requirements for Measurement Standards and Test Equipment

Each test procedure presented in this handbook includes a list of the equipment needed to perform the inspection. The scales and other measurement standards used (e.g., balances, mass standards, volumetric, and linear measures) to conduct any test must be traceable to the International System of Units (SI), usually through the National Institute of Standards and Technology (NIST). Standards must be used in the manner for which they were designed and calibrated.

1.7.2. Certification Requirements for Standards and Test Equipment

All measurement standards and test equipment identified in this handbook or associated with the test procedures must be calibrated or standardized before initial use. This must be done according to the calibration procedures and other instructions found on NIST’s Laboratory Metrology and Calibration Procedures website at www.nist.gov/pml/weights-and-measures/laboratory-metrology/calibration-procedures or using other recognized procedures (e.g., those adopted for use by a state weights and

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measures laboratory). After initial certification, the standards must be routinely recertified according to your agency’s measurement assurance policies.


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Chapter 2. Test Procedures – Packages Labeled by Weight – Gravimetric Testing

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Chapter 2. Test Procedures for Packages Labeled by Weight - Gravimetric Testing

Scope

The gravimetric test method uses weight measurement to determine the net quantity of contents of packaged goods. This chapter includes general test methods to determine the net quantity of contents of packages labeled in terms of weight. Gravimetric testing is the preferred method of testing most products because it reduces destructive testing and improves measurement accuracy.

Measurement Standards and Test Equipment

2.2.1. Scale Requirements

Use a scale (for this handbook the term “scale” includes balances) that has at least 100 scale divisions. It must have a load-receiving element of sufficient size and capacity to hold the packages during weighing. It also requires a scale division no larger than 1/6 of the Maximum Allowable Variation (MAV) for the package size being weighed. The MAV/6 requirement ensures that the scale has adequate resolution to determine the net contents of the packages. Subsequent references to product test results requiring the agreement to within one scale division are based on scale divisions that are equal to or only slightly smaller than the MAV/6. (See Appendix A, Table 2-5. “Maximum Allowable Variations (MAVs) for Packages Labeled by Weight.”)

Example: The MAV for packages labeled with a net weight 113 g (0.25 lb) is 7.2 g (0.016 lb). Divide (÷) the MAV by 6 to obtain the maximum scale division that can be used to determine the gross, tare and net weights for a package size.

7.2 g (0.016) ÷ 6 = 1.2 g (0.002 lb)

In this example, a 1 g (0.002 lb) scale division would be the maximum scale division appropriate for weighing these packages.

(Amended 2010)

2.2.2. Scale Accuracy

Verify the accuracy of a scale before each initial daily use, each use at a new location, or when there is any indication of abnormal equipment performance (e.g., erratic indications). Recheck the scale accuracy if it is found that the lot does not pass, so there can be confidence that the test equipment is not at fault.

Scales used to check packages must meet the acceptance tolerances specified for their accuracy class in the current edition of NIST Handbook 44 (HB 44) “Specifications, Tolerances, and Other Technical Requirements for Weighing and Measuring Devices.” The tolerances for Class II and Class III scales are presented in NIST HB 44, Section 2.20. Scales, “T.N. Tolerances Applicable to Devices Marked I, II, III, III L, and IIII.”


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Note: If the package checking scale is not marked with a “class” designation, use Table 2-1. “Class of Scale” to determine the applicable tolerance.

Always use good weighing and measuring practices. For example, be sure to use weighing and measuring equipment according to the manufacturer’s instructions and make sure the environment is suitable. Place scales and other measuring equipment (e.g., flasks and volumetric measures) on a rigid support and maintain them in a level condition if being level is required to ensure accuracy.

2.2.3. Scale Tolerance

Follow this procedure to determine the scale tolerance:

1. Determine the total number of divisions (i.e., the minimum increment or graduation indicated by the scale) of the scale by dividing the scale’s capacity by the minimum division.

Example: A scale with a capacity of 5000 g and a minimum division of 0.1 g has 50 000 divisions.

5000 ÷ 0.1 g = 50 000 division 2. From Table 2-1. “Class of Scale”, determine the class of the scale using the minimum scale

division and the maximum number of scale divisions.

Example: On a scale with a minimum division of 0.1 g and 50 000 total scale divisions the appropriate class is “II.”

Note: If a scale is used where the number of scale divisions is between 5001 and 10 000 and the division size is 0.1 g or greater and is not marked with an accuracy Class II marking, Class III scale tolerances apply. 3. Determine the number of divisions for any test load by dividing the value of the mass

standard being applied by the minimum division indicated by the scale.

4. Determine the tolerance from Table 2-2. “Acceptance Tolerances for Class of Scale Based on Test Load in Divisions” in divisions appropriate for the test load and class of scale

Example: If the scale has a minimum division of 0.1 g and a 1500 g mass standard is applied, the test load is equal to 15 000 divisions (1500/0.1). On a Class II scale with a test load between 5001 and 20 000 divisions, Table 2-2. “Acceptance Tolerances for Class of Scale Based on Test Load in Divisions” indicates the tolerance is plus or minus one division.

Chapter 2. Test Procedures – Packages Labeled by Weight - Gravimetric Testing

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Table 2-1. Class of Scale

Value of Scale Division1 Minimum and Maximum Number of

Divisions Class of Scale Minimum Maximum

1 mg to 0.05 g 100 100 000 II 0.1 g or more 5000 100 000 II 0.1 g to 2 g

0.000 2 lb to 0.005 lb 0.005 oz to 0.125 oz

100 10 000 III

5 g or more 0.01 lb or more 0.25 oz or more

500 10 000 III

1On some scales, manufacturers designated and marked the scale with a verification division (e) for testing purposes (e = 1 g and d = 0.1 g). For scales marked Class II, the verification division is larger than the minimum displayed division. The minimum displayed division must be differentiated from the verification scale division by an auxiliary reading means such as a vernier, rider, or at least a significant digit that is differentiated by size, shape, or color. Where the verification division is less than or equal to the minimum division, use the verification division instead of the minimum division. Where scales are made for use with mass standards (e.g., an equal arm balance without graduations on the indicator), the smallest mass standard used for the measurement is the minimum division.

Table 2-2.

Acceptance Tolerances for Class of Scale Based on Test Load in Divisions

Test Load in Divisions Tolerance Class II Scale Class III Scale

0 to 5000 0 to 500 Plus or Minus 0.5 Division

5001 to 20 000 501 to 2000 Plus or Minus 1.0 Division

20 001 or more 2001 to 4000 Plus or Minus 1.5 Divisions

Not Applicable 4001 or more Plus or Minus 2.5 Divisions

2.2.4. Scale Verification

Use the following procedures to verify the scale. These procedures, which are based on those required in NIST Handbook 44, have been modified to reduce the amount of time required for testing scales in field situations.

Do not use a scale if it has an error that exceeds the specified tolerance in Table 2-2 in any of the performance tests described in the following section.

Handbook 133, Checking the Net Contents of Packaged Goods (2